Central Research Department, Experimental Station, E. I. du Pont de Nemours and Company, Wilmington, Delaware 19898.
Plant Physiol. 1973 Jul;52(1):1-5. doi: 10.1104/pp.52.1.1.
Three types of whole plant experiments are presented to substantiate the concept that an important function of ethylene in abscission is to reduce the transport of auxin from the leaf to the abscission zone. (a) The inhibitory effect of ethylene on auxin transport, like ethylene-stimulated abscission, persists only as long as the gas is continuously present. Cotton (Gossypium hirsutum L. cv. Stoneville 213) and bean (Phaseolus vulgaris L. cv. Resistant Black Valentine) plants placed in 14 mul/l of ethylene for 24 or 48 hours showed an increase in leaf abscission and a reduced capacity to transport auxin; but when returned to air, auxin transport gradually increased and abscission ceased. (b) Ethylene-induced abscission and auxin transport inhibition show similar sensitivities to temperature. A 24-hour exposure of cotton plants to 14 mul/l of ethylene at 8 C resulted in no abscission and no significant inhibition of auxin transport. Increasing the temperature during ethylene treatment resulted in a progressively greater reduction in auxin transport with abscission occurring at [unk]27 C where auxin transport was inhibited over 70%. (c) Auxin pretreatment reduced both ethylene-induced abscission and auxin transport inhibition. No abscission occurred, and auxin transport was inhibited only 18% in cotton plants which were pretreated with 250 mg/l of naphthalene acetic acid and then placed in 14 mul/l of ethylene for 24 hours. In contrast, over 30% abscission occurred, and auxin transport was inhibited 58% in the corresponding control plants.Collectively, the results presented here and elsewhere indicate that ethylene regulates the sensitivity of the cells in the abscission zone to the more direct actions of the gas (e.g., enzyme induction, secretion) by reducing auxin transport.
提出了三种全株植物实验，以证实乙烯在脱落过程中的一个重要功能是减少生长素从叶片向脱落区的运输。（a）乙烯对生长素运输的抑制作用，就像乙烯刺激的脱落一样，只要气体持续存在就会持续存在。棉花（Gossypium hirsutum L. cv. Stoneville 213）和菜豆（Phaseolus vulgaris L. cv. Resistant Black Valentine）植物在 14 μl/L 的乙烯中放置 24 或 48 小时，表现出叶片脱落增加和生长素运输能力降低；但当返回空气时，生长素运输逐渐增加，脱落停止。（b）乙烯诱导的脱落和生长素运输抑制对温度表现出相似的敏感性。棉花植物在 8°C 下暴露于 14 μl/L 的乙烯 24 小时，不会导致脱落，也不会显著抑制生长素运输。在乙烯处理过程中升高温度会导致生长素运输逐渐减少，脱落发生在 27°C 时，生长素运输抑制超过 70%。（c）生长素预处理可减少乙烯诱导的脱落和生长素运输抑制。在棉花植物中，用 250mg/L 的萘乙酸预处理，然后在 14 μl/L 的乙烯中放置 24 小时，不会发生脱落，生长素运输仅被抑制 18%。相比之下，超过 30%的脱落发生，而对照植物中生长素运输抑制 58%。综上所述，这里和其他地方提出的结果表明，乙烯通过减少生长素运输来调节脱落区细胞对气体更直接作用（例如酶诱导、分泌）的敏感性。
